Kidding aside, there was some line in the Bible about something-something-four-corners-of-the-earth and some 1850s? Bible literalists took the "EVERY WORD IS TRUE" bit a little too seriously.

Or, "If every word isn't true, does that mean hating the gays is my problem?"

I'm just about convinced that's relevant to at least some of them: They really, really need the "ritual purity" parts of the Bible to be "correct" in their sense of the term, which means that ritual purity is the same as moral rectitude, which means that their hatred of "abnormal" or "unclean" sexual behavior isn't just them, it's due to their inherent Godliness, as opposed to their exaggerated disgust response being inborn and the cause of their conservatism.

For that to be true, the Bible must be completely unimpeachable, or else someone would be able to poke holes in the whole thing, concluding that, while homosexual behavior is known in the animal kingdom and that plenty of historical cultures have been accepting of homosexuality, homophobia is a moral fad, something limited to a relative few places and times.

And if homophobia is just a fad, their hatred is on their own heads. Their obsession is on their own heads. They can't justify it by saying the Being What Is Who Am says being gay is wrong.

So. "Gays make me feel ooky, therefore the world is flat." Hey, it's just as reasonable as the idea that Jesus finds the inheritance tax a moral abomination.